Miniature momentary rotary type switch for resetting electronic watch digital display

ABSTRACT

A switch having planar contacts and a rotary brush engageable with the contacts to perform a switching function has printed circuit board mounting lugs integral with planar contact circuitry. The lugs allow mounting of the switch to the edge of the printed circuit board and is of miniature size suitable for use with a watch stem of an electronic wristwatch. Tactile feel and positive detent of the switch rotor is provided with a resilient beam which detents against the irregular surface of a cam provided on the rotor. The cam has an offset finger that resiliently deflects a return spring which returns the switch rotor to an off position providing only a momentary switching function when the rotor is manually rotated and then released. The switch parts are designed for stackable assembly without a need for fasteners. The switching function, in this instance, is associated with resetting of the hour and minute time display.

United States Patent 1 1 Lockard [451 July 1, 1975 [75] Inventor: Joseph Larue Lockard, Harrisburg,

[73] Assignee; AMP Incorporated, Harrisburg, Pa,

[22] Filed: Mar. 15, I974 [21] Appl. No.: 451,617

[52] US. Cl 200/11 R; 58/57; 200/11 DA; 200/17 R; 200/153 V [51] Int. (31. HOII-I 21/38; G04C 23/00 [58] Field of Search 200/11, 63 R, 63 A, 65, 200/66, 67 C, 153 V, 153 LB, 291, 284,17 R, 153 K, 73

[56] References Cited UNITED STATES PATENTS 2,121,671 6/1938 Schwarze 200/11 C X 3,214,536 10/1965 Wallace 200/11 C 3,271,531 9/1966 Winogrocki et a1. 200/11 C X 3,271,534 9/1966 McFadden 200/11 H 3,284,534 11/1966 Didyk 200/291 X 3,470,333 9/1969 Schneider et a1, 200/291 X 3,506,798 4/1970 Cherry 200/63 R 3,643,044 2/1972 Balcheller 200/11 C X FOREIGN PATENTS OR APPLICATIONS 1,013,961 12/1965 United Kingdom 200/65 Primary Examiner-James R Scott Attorney, Agent, or FirmGerald K. Kita [57] ABSTRACT A switch having planar contacts and a rotary brush engageable with the contacts to perform a switching function has printed circuit board mounting lugs integral with planar contact circuitry. The lugs allow mounting of the switch to the edge of the printed circuit board and is of miniature size suitable for use with a watch stem of an electronic wristwatch. Tactile feel and positive detent of the switch rotor is provided with a resilient beam which detents against the irregular surface of a cam provided on the rotor. The cam has an offset finger that resiliently deflects a return spring which returns the switch rotor to an off position providing only a momentary switching function when the rotor is manually rotated and then released. The switch parts are designed for stackable assembly without a need for fasteners. The switching function, in this instance, is associated with resetting of the hour and minute time display.

3 Claims, 11 Drawing Figures 1 MINIATURE MOMENTARY ROTARY TYPE SWITCH FOR RESETTING ELECTRONIC WATCH DIGITAL DISPLAY The present invention relates to a momentary switch of miniature size especially adapted for edge mounting to a printed circuit board. The component parts of the switch are designed for stacked assembly with the contact circuitry of the switch being generally planar and provided with mounting lugs for mounting the circuitry to the edge of the printed circuit board. Such a construction particularly adapts the switch for use in a low profile electronic device such as an electronic wristwatch.

BACKGROUND OF THE PRIOR ART Solid state electronics has advanced to the point where an electronic timepiece and an instantaneous digital readout may be miniaturized for packaging within a device as small as a wristwatch. As in conventional watch designs, a watch stem is utilized to syn chronize the time display with the correct time. In an electronic watch, the displayed time is synchronized by manually switching the digital display to a rapid number sequencing mode whereby the displayed numbers are quickly rolled over until the correct hour and minute time is displayed in sequence with correct time. The watch stem of the electronic watch thus is utilized as a manually actuated switch to switch the numerical display to its rapid operational mode. Thus there has existed a need in the prior art for a switch of miniature size which would interface with a watch stern and the operational circuitry of an electronic watch. Generally the hour display and the minute display are synchronized individually, requiring a four-position switch to perform such individual operations.

BRIEF DESCRIPTION OF THE INVENTION To achieve a low profile the electronics of a digital display watch are mounted on a planar printed circuit board. When the printed circuit board is contained within a wristwatch case, the stem of the watch projects through a side of the case and generally faces the edge of the printed circuit board. Accordingly the miniature switch according to the present invention must interface between the stern and an edge of the printed circuit board. This is accomplished by making the switch contacts in the form of planar circuitry, with the circuitry being provided with mounting lugs for receipt over and attachment to the printed circuit board edge. Also since the switch must be made of miniature size, the switch components are fabricated for assembly in stacked layers without the need for fasteners. The switch further incorporates a rotor which is turned by manual rotation of the watch stem. A return spring is incorporated into the switch such that once the numerical display is synchronized with the correct time, the watch stem is released and the return spring rotates the rotor of the switch to an off position. To ensure a tactile feel to the watch stem. for an indication that the switch is correctly actuated, a cam is provided on the rotor. A resilient beam mounted in the switch is resiliently engaged against the irregular surface of the cam and detents against the cam surface as the rotor is turned to its switching function.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide a momentary contact switch capable of miniaturization for interface between a watch stem and the electronic circuitry of an electronically driven digital readout timepiece.

Another advantage of the present invention is to provide a miniature rotary switch the components of which are assembled in stacked layers without a need for fasteners and wherein the switch contacts provide integral projecting mounting lugs adapting the switch for direct connection to a printed circuit board edge.

Another object of the present invention is to provide a miniature rotary switch having a manually rotatable rotor assembly provided with an irregular cam surface, with a resilient spring resiliently engaging and detentin g against the cam surface to provide a tactile feel during manual rotation of the rotor in the performance of a switching function, and where the switch is provided with a return spring engageable against the rotor assembly for positively turning said rotor assembly to an off position and thereby proviide a momentary switching operation.

Another object of the present invention is to provide a miniature momentary contact switch fabricated from components assembled in stacked layers assembled without a need for separate fasteners.

Another object of the present invention is to provide a rotary switch with switch contacts in the form of planar circuitry and a manually rotatable rotor assembly having brushes which are rotated into selective engagement with circuitry to perform a switching function, with the switch further including a resilient member which detents against an irregular cam surface of the rotor assembly to provide a tactile feel to rotation of the rotor assembly during the performance of a switching operation.

Other objects and many attendant advantages of the present invention will become apparent upon perusal of the following detailed description taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary enlarged perspective with parts broken away to illustrate the details thereof of a watch incorporating the switch according to the present invention;

FIG. 2 is an enlarged perspective of an assembled switch according to the present invention;

FIG. 3 is an enlarged perspective of the switch with parts illustrated in exploded configuration;

FIGS. 4 A, 4 B, and C are enlarged bottom plan views illustrating the operational positions of the switch according to the present invention;

FIG. 5 is a section taken along the lines 5-5 of FIG. 4A;

FIG. 6 is a top plan view of the base and attached circuitry according to the present invention;

FIG. 7 is a blank of the brush contacts of the switch according to the present invention;

FIGS. 8 and 9 are elevations illustrating assembly of the brush contacts to the rotor according to the present invention.

DETAILED DESCRIPTION With more particular reference to the drawings the switch includes a plurality of switch poles in a planar circuit generally indicated at I. The circuit includes a carrier strip 2 having pilot holes 4. The carrier strip is in the form of the familiar ladder strip configuration with the switch pole circuitry generally indicated at 6, comprising a first arcuate segment contact 8 and a sec ond contact 10 also generally an arcuate segment and concentric with the contact 8. The contacts 8 and 10 include radial portions l2 and 14 which terminate in tab portions 16 and 18 which are bent out of the plane of the circuitry 6 to form resilient cantilever beams. The tab 16 and 18 may be formed during the stamping and forming operation utilized to fabricate the circuitry 6 and provide mounting lugs for receipt over the edge of the printed circuit board to be described. A pair of additional contacts 20 and 22 are of segmented arcuate configuration and are generally concentric with respect to each other. The contact 20 is radially outwardly spaced from the contact 8 and is provided with a gener ally radial segmented portion 24 terminating in a projecting tab portion 26. The contact 22 is adjacent the contact 10 and includes a generally radial portion 28 which terminates in a projection tab portion 30. The tab portions 26 and 30 are bent out of the plane of the circuitry 6 and provide resilient cantilever beams received over the edge of a printed circuit board. In assembly the circuitry 6 is placed over a molded dielectric base portion 32 the top surface 34 which is pro vided with recessed channels 7 of a shape complimentary to the circuitry 6 which is contained in the channels. The base includes a plurality of projecting posts 36 which may be molded integral with the base portion 32 to provide locating pins projecting through appro priate apertures of the circuitry 38 in order to locate the circuitry in proper position of the base. When the circuitry 6 is laid in registration over the posts 38 and in the channels of the base portion 32, the carrier strip 2 is utilized to maintain the circuitry in proper shape during assembly on the base portion. Accordingly the carrier strip 2 may be removed and discarded.

As shown, the base portion 32 is provided on opposite sides thereof with a pair of aligned cutouts 40 and 42 into which the projecting tab portions 16 and 18 and 26 and 30 project.

As more particularly shown in the figure there is provided a molded cam having a relatively enlarged plate portion 44 the perimeter surface 26 of which is of irregular configuration. At one end of the plate portion 44 is provided an integral cylindrical finger 48 which is offset from an elongated shaft 50 which projects from the plate portion 44. The shaft 50 is provided with an enlarged stepped portion 52 which is generally cylindrical and located adjacent to the plate portion 44. A wire spring 54 is coiled one and onehalf turns around the stepped portion 52 with the free ends 56 and 58 of the spring projecting outwardly and generally radially from the stepped portion 52.

The base portion 32 is provided with a central aperture 60 which receives the central shaft 50 of the cam therethrough. The base further is provided with a recessed bottom wall 62 against which the enlarged portion 52 of the cam is seated. The coil spring 54 is therefore retained in the space between the plate portion 44 and the bottom wall 62. The base is further provided with a pair of projecting stops 64 and 66 which are molded integral with the base portion 32 against which the ends 56 and 58 of the spring 54 are seated. The ends 56 and 58 are maintained in resilient compression between the respective stops 64 and 66 providing a preload on the spring 54. The bottom wall 62 of the base portion is further recessed in an arcuate configuration. As shown at 68 the projecting finger 48 of the cam projects for arcuate displacement within the recessed portion 68 when the cam is rotated about its shaft 50 in a manner to be explained. The irregular surface 46 of the cam is provided with a projecting portion 70 flanked by two flat surfaces 72 and 74. The base is provided with a resilient leaf spring 76 in the form of an end supported resiliently deflectable beam the ends of which are contained within recessed pockets 78 and 80 provided integral with the base portion 32. The beam 76 is maintained in continuous resilient engagement against the irregular cam surface 46 for a purpose to be described.

As shown the shaft 50 is provided with a reduced end portion of rectangular cross-section 82 which is received within a rectangular recess 84 of a molded rotor portion 86. As shown in the figure, the rotor portion 86 is fabricated with an enlarged cylindrical hub portion 88 which is provided with an outwardly encircling flange portion 90. A pair of brush contacts have integral portions 92 and 94 which are impressed against the flange portion 90 of the rotor portion 86. Each of the contacts 92 and 94 include projecting integral stern portions 96 and 98 to which are attached corresponding pairs ")0 and 102 of resiliently deflectable brush type contacts which are outwardly dimpled at their tips to provide arcuate contact surfaces. The stem portions 96 and 98 ofthe contacts are then bent in encirclement over the flange portion 90 of the rotor portion for retention to the rotor portion. The rotor portion includes a reduced cylindrical projecting hub portion 104 adjacent to the tips of the contacts and 102. A central aperture 106 of the hub 86 is received over the reduced portion 82 of the cam portion. The reduced hub portion 104 provides a sliding bearing surface against a corresponding circular bearing surface 106 provided by the base portion 32 in encirclement around the central aperture 60 of the base portion. The brush type contacts 100 and 102 are therefore pressed against the circuitry 6, with the circuitry and the brushed contacts being retained between the bearing surface 106 and the flange portion 90 of the hub portion 86. The end 108 of the shaft portion 82 is enlarged such as by peening or heat-staking to form an enlarged head preventing removal of the hub portion 86 from the shaft portion 82. Together the cam and rotor portion 86 provide a rotor assembly which bridges across the base portion 32 and the circuitry 6. The rotor portion 86 and the cam are rotatable together about the shaft 50, causing the irregular surface 46 of the cam to traverse over the resilient beam 76. Rotation of the rotor assembly causes the brushes 100 and 102 to slidably traverse over the circuitry for desired contact with the contact portions 8, 10, 20, and 22 of the circuitry as desired. For example, brush 100 may bridge across contact portions 8 and 20 and brush 102 across contact portion 10 and 22.

In operation refer to FlGS. 4A, 4B and 4C. the projecting portion of the cam irregular surface 46 provides a tactile feel for the manual rotation of the rotor assemblyv More particularly, rotation of the projecting por tion 70 against the resilient beam 76 causes a substantial resilient deflection of the beam such that continued rotation of the rotor assembly will cause the resilient beam to resiliently spring back and detent against either the flat surfaces 72 or 74, as the rotor assembly is rotated. Such detent action provides a tactile feel to rotation of the rotor assembly. The projecting finger 48 is rotated through an arc and resiliently deflects the springends 58 or 56 as the resilient beam 76 detents into and against either the flat portion 74 or the flat surface 72. The resiliently deflected spring 54 thus stores resilient spring energy which provides a return rotation of the rotor assembly. Thus as the rotor assembly is manually rotated to either of its detented positions the return spring will tend to cause return rotation. Such return rotation occurs until the spring ends 56 and 58 are stopped against the stops 66 and 64. Safety stops are provided by projection 104 on arcuate blocks 106 mounted on the posts 36. The rotor has projections 108 which stop against the projections 104 when the rotor is turned. The projecting finger 48 will be biased into engagement against either of the spring legs 56 or 58, since the resilient beam 76 will resiliently detent slightly on either side of the projecting portion 70. Thus when the projecting portion 70 is engaged against the beam 76, such a position is unstable and the cam will be biased by the beam 76 to a rotation until the beam detents slightly on either side of the projecting portion 70 and also until the projecting finger 48 is stopped against either one of the spring legs 56 or 58 which are in turn stopped against the stops 64 and 66. Thus there is provided a four position momentary switch, with an automatic return to either of two positions provided by the resilient stored energy of the return spring 54. Any manual rotation between such two positions provides a lost motion action so as to prevent confusion between the two positions by an operator of the switch, and also to provide a tactile feel as the projection 70 is forcibly rotated past engagement on the resilient beam 76. The projecting tab portions 16 and 18 and 26 and 30 may be received over a printed circuit board edge shown in phantom outline at 110. The tab portions resiliently grip against the printed circuit board and may be soldered to the circuitry thereon to provide desired electrical connections externally of the switch. The shaft 50 of the rotor assembly may connect in any wellknown manner to a watch stem.

Although preferred embodiments and modifications of the switch according to the present invention have been specifically shown and described, other modifications and embodiments which will apparent from my perusal of the following claims is intended to be covered by the spirit and scope of the invention.

What is claimed is:

l. A switch, comprising:

a base having recessed portions,

coplanar circuits secured to said base and defining a plurality of switch poles,

portions of said circuits projecting outwardly of the plane of said circuits and into said recess portions to provide mounting lugs,

a cam having a shaft received rotatably through said base,

a rotor mounted on said shaft having brush contacts thereon engageable selectively on said circuits upon rotation of said rotor,

said circuits being interposed between said cam and said rotor, and

resilient means encircling said shaft and having end portions engaged on said base, said cam being rotatable from a central position in either of two directions biasing resiliently the corresponding end portions of said spring means to store resilient spring energy for return rotation of said cam to said central position.

2. The structure as recited in claim 1, and further including:

two stop means on said base defining limits to rotation of said cam, said cam being engageable on respective stop means to limit rotation thereof in said two directions.

3. The structure as recited in claim 2, and further including:

at least a pair of blocks secured to said base and rotatably receiving said rotor therebetween, said blocks having stops thereon defining limits to rotation of said rotor, and said rotor having a projection engageable on a corresponding stop upon rotation of said cam from said central position. 

1. A switch, comprising: a base having recessed portions, coplanar circuits secured to said base and defining a plurality of switch poles, portions of said circuits projecting outwardly of the plane of said circuits and into said recess portions to provide mounting lugs, a cam having a shaft received rotatably through said base, a rotor mounted on said shaft having brush contacts thereon engageable selectively on said circuits upon rotation of said rotor, said circuits being interposed between said cam and said rotor, and resilient means encircling said shaft and having end portions engaged on said base, said cam being rotatable from a central position in either of two directions biasing resiliently the corresponding end portions of said spring means to store resilient spring energy for return rotation of said cam to said central position.
 2. The structure as recited in claim 1, and further including: two stop means on said base defining limits to rotation of said cam, said cam being engageable on respective stop means to limit rotation thereof in said two directions.
 3. The structure as recited in claim 2, and further including: at least a pair of blocks secured to said base and rotatably receiving said rotor therebetween, said blocks having stops thereon defining limits to rotation of said rotor, and said rotor having a projection engageable on a corresponding stop upon rotation of said cam from said central position. 